2-arylmethylazetidine carbapenem derivatives and preparation thereof

ABSTRACT

A 2-arylmethylazetidine carbapenem derivative of formula (I) or a pharmaceutically acceptable salt thereof exhibits a wide spectrum of antibacterial activities against Gram-positive and Gram-negative bacteria and excellent antibacterial activities against resistant bacteria such as methicillinresistant  Staphylococcus aureus  (MRSA) and quinolone-resistant strains (QRS):

FIELD OF THE INVENTION

The present invention relates to 2-arylmethylazetidine carbapenemderivatives having a wide spectrum of antibacterial activities againstGram-positive and Gram-negative bacteria and excellent antibacterialactivities against resistant bacteria such as methicillin-resistantStaphylococcus aureus (MRSA) and quinolone-resistant strains (QRS); aprocess for the preparation thereof; and an antibiotic compositioncomprising same.

BACKGROUND OF THE INVENTION

Since penicillin was firstly used clinically in 1940s, it had been knownas a miracle medicine saving many lives against infectious diseases.However, it was not long till Staphylococcus aureus having resistanceagainst penicillin appeared. In 1960s, methicillin, semi-syntheticpenicillin, was developed and used to treat infectious diseases causedby penicillin-resistant Staphylococcus aureus, and in 1973, cefazolinwas developed. But, methicillin-resistant Staphylococcus aureus (MRSA)and cefazolin-resistant strain appeared, and a number of antibioticsincluding cephalosporin, quinolone, carbapenem, monobactam and glycosidehave been developed to deal with the resistant bacteria. However,penicillin-resistant Streptococcus pneumococcus, MRSA and otherantibiotics-resistant bacteria continued to cast problems over theworld.

Therefore, there has been a continual need to develop still newantibiotics having antibacterial activity against not only Gram-positiveand Gram-negative bacteria but also resistant bacteria. Recently, it wasreported that 2-arylcarbapenem compounds (L-695256 and L-742728, MERCK)showed good activity against MRSA, VRSA and VRE (Hugh rosen et al.,Sciences, 703(1999)). WO 99/62906 reports that 2-benzothiazolethenylcarbapenem has good activity against MRSA. In addition, many antibioticsderived from carbapenem have been reported to show some activity againstMRSA. For example, imipenem and meropenem are effective in treatinginfection by MRSA having weak resistance.

Accordingly, the present inventors have endeavored to develop anantibiotic having a wide spectrum of antibacterial activities againstGram-positive and Gram-negative bacteria, which can be used to treatinfection by resistant bacteria such as MRSA.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide acarbapenem derivative, which has excellent antibacterial activity andcan be used to treat infection by resistant bacteria such as MRSA andQRS.

Another object of the present invention is to provide a process for thepreparation of said carbapenem derivative.

A further object of the present invention is to provide an antibioticcomposition comprising said carbapenem derivative as an activeingredient.

In accordance with one aspect of the present invention, there isprovided a 2-arylmethylazetidine carbapenem derivative of formula (I) ora pharmaceutically acceptable salt thereof:

wherein,

R₁ is hydrogen, or one or more substituents selected from the groupconsisting of C₁₋₃ alkyl, C₁₋₃ alkyloxy, hydroxyl, amine, alkylamine,alkylthiol, trifluoromethyl and halogen; and

R₂ is hydrogen or C₁₋₃ alkyl.

In accordance with another aspect of the present invention, there isprovided a process for the preparation of said carbapenem derivative,and an antibiotic composition comprising said carbapenem derivative orits pharmaceutically acceptable salt as an active ingredient.

DETAILED DESCRIPTION OF THE INVENTION

Examples of the desirable compounds of formula (I) according to thepresent invention are:

-   Potassium(1R,5S,6S)-2-(1-benzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(4-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(3-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(2-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(3,4-dimethoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(4-chlorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(4-fluorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(3-trifluoromethylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-{1-[(1R)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-{1-[(1S)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;-   Potassium(1R,5S,6S)-2-[1-(4-methylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;    and-   Potassium(1R,5S,6S)-2-{1-[1-(4-bromophenyl)ethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate.

The 2-arylmethylazetidine carbapenem derivative of the present inventionmay be prepared by a process comprising the steps of:

(a) subjecting compounds of formula (II) and formula (III) to acondensation reaction to obtain a carbapenem ester derivative of formula(IV); and

(b) removing the carboxyl protecting group and the optional hydroxylprotecting group from the compound of formula (IV).

wherein,

R₁ and R₂ have the same meanings as defined above;

R₃ is hydrogen or a hydroxyl protecting group; and

R₄ is a carboxyl protecting group.

In the above process, the hydroxyl protecting groups may be one of thecommon hydroxyl protecting groups such as tert-butyldimethylsilyl andtriethylsilyl groups, and the carboxyl protecting group may be one ofthe common carboxyl protecting groups such as p-nitrobenzyl, allyl andp-methoxybenzyl groups.

The condensation betweenp-nitrobenzyl-2-diphenylphosphoryl-6-tert-butyldimethylsilyloxyethyl-1-methyl-2-carbapenem-3-carboxylateof formula (II) (R₃=tert-butyldimethylsilyl, R₄=p-nitrobenzyl) and1-allylmethyl-3-mercapto-azetidine derivative of formula (III) can becarried out in accordance with a conventional method.

For instance, the compound of formula (III) is dissolved in an anhydrousorganic solvent, e.g., acetonitril, methylene chloride, tetrahydrofuranor acetone, preferably acetonitril, and cooled to a temperature rangingfrom −20° C. to 0° C. N,N-diisopropylethylamine or triethylamine isslowly added to the resulting solution, and the compound of formula (II)is added thereto. The above mixture is stirred at a temperature rangingfrom −20° C. to 0° C. for 2 to 4 hours, and the resulting product isseparated in accordance with a conventional method to obtain thecompound of formula (IV).

The hydroxyl protecting group (R₃) and the carboxyl protecting group(R₄) may be removed sequentially from the compound of formula (IV) inaccordance with conventional methods, or, in case when the hydroxylgroup is not protected, only the carboxyl protecting group is removed toobtain the compound of formula (I).

For instance, in case when a triethylsilyl hydroxyl protecting group(R₃) and a carboxyl protecting group (R₄) are to be removedsequentially, the compound of formula (IV) is dissolved in a mixture oftetrahydrofuran and water (4:1 (V:V)), an equivalent amount of 1 Maqueous trifluoroacetic acid solution is added thereto, and theresulting solution is stirred at room temperature for 30 to 60 min toremove the hydroxyl protecting group. Then, when R₄ is a p-nitrobenzylgroup, it may be removed by catalytic hydrogenation, and when R₄ is anally group, it may be removed by reacting the compound of formula (IV)with triphenylphosphine or tetrakis(triphenylphosphine)palladium underthe presence of an organic acid or its salt (e.g., acetic acid,2-ethylhexanonic acid and a sodium or potassium salt thereof).

The resulting compound may be purified by reverse-phase silica gelcolumn chromatography, and lyophilized to obtain the compound of theformula (I) as an amorphous solid.

The compound of the formula (III) used in the present invention may beprepared according to Scheme (I).

wherein,

R₁ and R₂ have the same meanings as defined above.

Specifically, an aromatic amine (a compound of formula (V)) andepichlorohydrin are added to an organic solvent, the mixture is stirredfor 24 to 48 hours to obtain a solid product, and the product isfiltered to obtain a compound of formula (VI). The compound of formula(VI) and N-trimethylsilylacetamide are heated in an organic solvent for3 to 5 hours, and the product is distilled under a reduced pressure toobtain a compound of formula (VII). Examples of the organic solvent usedin the above reactions include ethyl ether, petroleum ether and ligroin,and petroleum ether is preferable.

The compound of formula (VII) is then dissolved in an organic solventsuch as acetonitrile, tetrahydrofuran and methylene chloride, preferablyin acetonitrile. An organic base such as triethylamine anddiisopropylethylamine, preferably triethylamine, is added thereto, andthe mixture is refluxed for 3 to 5 days to obtain a compound of formula(VIII). The compound of formula (VIII) is dissolved in an alcohol suchas methanol and ethanol, preferably methanol, and an alkali such assodium methoxide, lithium hydroxide and potassium tert-butoxide,preferably sodium methoxide, is added thereto. The mixture is stirred atroom temperature for 30 min to 1 hour to obtain a compound of formula(IX), which is subsequently subjected to the Mitsunobu reaction toobtain a compound of formula (X). Specifically,diisopropylazodicarboxylate is added to a solution of triphenylphosphinein anhydrous tetrahydrofuran, and the mixture is reacted at 0° C. for 1hour. Thioacetic acid and the compound of formula (IX) are addedthereto, and the resulting mixture is reacted at room temperature for 2to 4 hours to obtain a thioacetate derivative of formula (X).

The compound of formula (X) is then hydrolyzed by treating with aconventional base (e.g., 2 N potassium hydroxide or sodium hydroxide) inan alcohol to obtain a thiol compound of formula (III), which is usedfor the preparation of the compound of formula (IV) without furtherpurification.

The inventive compounds of formula (I) exhibit a wide spectrum ofantibacterial activities against Gram-positive and Gram-negativebacteria, and excellent antibacterial activity againstpenicillin-resistant Streptococcus pneumococcus, MRSA, QRSA andvancomycin-Resistant Enterococci (VRE).

Therefore, the present invention provides an antibacterial compositioncomprising a carbapenem derivative of formula (I) or itspharmaceutically acceptable salt as an active ingredient in combinationwith a pharmaceutically acceptable carrier.

The pharmaceutical composition of the present invention may include theactive ingredient in an amount of 0.1 to 75% by weight, preferably 1 to50% by weight, based on the total weight of the composition.

The pharmaceutical composition of the present invention may beadministered orally or parenterally. An oral formulation may be in theform of a tablet, pill, soft or hard gelatin capsule, solution,suspension, emulsion, syrup, powder and the like, and the formulationmay include diluents (e.g., lactose, dextrose, sucrose, mannitol,sorbitol, cellulose and glycine), lubricants (e.g., silica, talc,stearic acid, a magnesium or calcium salt thereof and polyethyleneglycol). The tablet may include binders such as magnesium aluminumsilicate, starch paste, gelatin, tragacanth, methylcellulose, sodiumcarboxymethylcellulose and polyvinylpyrrolidin. The formulation mayadditionally include disintegrants such as starch, agar, and alginicacid or its sodium salt, mixture and/or absorbents, colorants, flavoringagents and sweeteners.

Also, a representative parenteral formulation is an injectionformulation, preferably an isotonic solution or suspension.

The pharmaceutical composition may be sterilized and/or includeadditives such as preservatives, stabilizers, wetting agents,emulsifiers, salts or buffers for osmotic control and any othertherapeutically useful materials. The composition may be formulated byemploying a conventional method such as mixing, granulating and coatingmethods.

A typical daily dose of the compound of formula (I) or apharmaceutically acceptable salt thereof may range from 2.5 to 100 mg/kgbody weight, preferably 5 to 60 mg/kg body weight in case of mammalsincluding human, and can be administered in a single dose or in divideddoses orally or parenterally.

The following examples are intended to further illustrate the presentinvention without limiting its scope.

Preparation Examples 1 to 12 Preparation of 1-substitutedbenzylamino-3-chloropropane-2-ol

Preparation Example 1 1-benzylamino-3-chloropropane-2-ol

Epichlorohydrin (39 ml, 0.5 mol) and benzylamine (54.6 ml, 0.5 mol) weredissolved in petroleum ether (500 ml), stirred at room temperature for48 hours, and filtered. The resulting solid product was dissolved intoluene (50 ml), and normal hexane (500 ml) was added to the resultingsolution to obtain the title compound as a crystalline form in a yieldof 43%.

¹H NMR (200 MHz, CDCl₃): δ 2.76 (m, 2H), 3.55 (d, J=5.3 Hz, 2H), 3.81(s, 2H), 3.86 (m, 1H), 7.32 (m, 5H).

The procedure of Preparation Example 1 was repeated employingappropriate starting materials to obtain the compounds of PreparationExamples 2 to 12, respectively.

Preparation Example 2 1-chloro-3-(4-methoxybenzylamino)propane-2-ol

Yield: 53.4%;

¹H NMR (200 MHz, CDCl₃): δ 2.79 (m, 2H), 3.55 (d, J=5.4 Hz, 2H), 3.76(s, 2H), 3.80 (s, 3H), 3.91 (m, 1H), 6.86 (d, J=8.4 Hz, 2H), 7.24 (d,J=8.4 Hz, 2H).

Preparation Example 3 1-chloro-3-(3-methoxybenzylamino)propane-2-ol

Yield: 48.7%;

¹H NMR (200 MHz, CDCl₃): δ 2.78 (m, 2H), 3.56 (d, J=5.5 Hz, 2H), 3.79(s, 2H), 3.81 (s, 3H), 3.86 (m, 1H), 6.82 (m, 3H), 7.21 (m, 1H).

Preparation Example 4 1-chloro-3-(2-methoxybenzylamino)propane-2-ol

Yield: 50.8%;

¹H NMR (200 MHz, CDCl₃): δ 2.71 (m, 2H), 3.51 (d, J=5.9 Hz, 2H), 3.79(s, 2H), 3.84 (s, 3H), 3.86 (m, 1H), 6.90 (m, 2H), 7.21 (m, 2H).

Preparation Example 5 1-chloro-3-(3,4-dimethoxybenzylamino)propane-2-ol

Yield: 38.6%;

¹H NMR (200 MHz, CDCl₃): δ 2.71 (m, 2H), 3.49 (d, J=5.5 Hz, 2H), 3.92(m, 9H), 6.80 (m, 3H).

Preparation Example 6 1-chloro-3-(4-chlorobenzylamino)propane-2-ol

Yield: 45.3%;

^(1H) NMR (200 MHz, CDCl₃): δ 2.78 (m, 2H), 3.58 (d, J=5.3 Hz, 2H), 3.78(s, 2H), 3.88 (m, 1H), 7.28 (m, 4H).

Preparation Example 7 1-chloro-3-(4-fluorobenzylamino)propane-2-ol

Yield: 34.4%;

¹H NMR (200 MHz, CDCl₃): δ 2.78 (m, 2H), 3.57 (d, J=5.3 Hz, 2H), 3.79(s, 2H), 3.90 (m, 1H), 7.01 (m, 2H), 7.29 (m, 2H).

Preparation Example 81-chloro-3-(3-trifluoromethylbenzylamino)propane-2-ol

Yield: 50.8%;

¹H NMR (200 MHz, CDCl₃): δ 2.79 (m, 2H), 3.60 (d, J=5.3 Hz, 2H), 3.87(m, 3H), 7.50 (m, 4H).

Preparation Example 9 1-chloro-3-[(1R)-1-phenylethylamino]propane-2-ol

Yield: 76.2%;

¹H NMR (200 MHz, CDCl₃): δ 1.39 (d, J=6.5 Hz, 3H), 2.60 (m, 2H), 3.51(m, 2H), 3.79 (m, 2H), 7.31 (m, 5H).

Preparation Example 10 1-chloro-3-[(1S)-1-phenylethylamino]propane-2-ol

Yield: 76.2%;

¹H NMR (200 MHz, CDCl₃): δ 1.39 (d, J=6.5 Hz, 3H), 2.61 (m, 2H), 3.51(m, 2H), 3.80 (m, 2H), 7.32 (m, 5H).

Preparation Example 11 1-chloro-3-(4-methylbenzylamino)propane-2-ol

Yield: 48%;

¹H NMR (300 MHz, CDCl₃): δ 2.24 (bs, 2H), 2.34 (s, 3H), 2.67˜2.86 (m,2H), 3.55 (d, J=5.4 Hz, 2H), 3.77 (d, J=1.8 Hz, 2H), 3.88 (m, 1H), 7.13(d, J=8.1 Hz, 2H), 7.18 (d, J=8.1 Hz, 2H).

Preparation Example 121-chloro-3-[1-(4-bromophenyl)ethylamino]propane-2-ol

Yield: 75%;

¹H NMR (300 MHz, CDCl₃): δ 1.34 (d, J=6.6 Hz, 3H) 2.58 (m, 2H), 3.52 (m,2H), 3.73 (m, J=5.1 Hz, 1H), 4.12 (dd, 1H) 7.15 (m, 2H), 7.41 (m, 2H).

Preparation Examples 13 to 24 Preparation of(3-chloro-2-trimethylsilyloxypropyl)-substituted arlylamine

Preparation Example 13 1-benzyl-(3-chloro-2-trimethylsilyl-propyl)-amine

1-Benzylamino-3-chloropropane-2-ol (42.2 g, 0.21 mol) prepared inPreparation Example 1 was dissolved in petroleum ether (700 ml).N-(trimethylsilyl)acetamide (30.5 g, 0.23 mol) was added thereto, andrefluxed with stirring for 3 hours. After removing solid precipitates byfiltration, the filtrate was concentrated under a reduced pressure toobtain 54 g (yield: 95%) of the title compound.

¹H NMR (200 MHz, CDCl₃): δ 0.51 (s, 9H), 3.08 (m, 2H), 3.78 (s, 2H),3.80 (m, 2H), 7.33 (m, 5H).

The procedure of Preparation Example 13 was repeated employing each ofthe compounds of Preparation Example 2 to 12 as a starting material toobtain the compounds of Preparation Examples 14 to 24, respectively.

Preparation Example 14(3-chloro-2-trimethylsilyloxypropyl)-(4-methoxybenzyl)amine

Yield: 97%;

¹H NMR (200 MHz, CDCl₃): δ 0.15 (s, 9H), 2.71 (m, 2H), 3.56 (m, 2H),3.74 (s, 2H), 3.80 (s, 3H), 3.96 (m, 1H), 6.85 (d, J=8.6 Hz, 2H), 7.23(d, J=8.4 Hz, 2H).

Preparation Example 15(3-chloro-2-trimethylsilyloxypropyl)-(3-methoxybenzyl)amine

Yield: 97.3%;

¹H NMR (200 MHz, CDCl₃): δ 0.15 (s, 9H), 2.75 (m, 2H), 3.52 (m, 2H),3.77 (s, 2H), 3.81 (s, 3H), 3.95 (m, 1H), 6.80 (m, 1H), 6.88 (m, 2H),7.26 (m, 1H).

Preparation Example 16(3-chloro-2-trimethylsilyloxypropyl)-(2-methoxybenzyl)amine

Yield: 86.7%;

¹H NMR (200 MHz, CDCl₃): δ 0.14 (s, 9H), 2.69 (m, 2H), 3.52 (m, 2H),3.79 (s, 2H), 3.83 (s, 3H), 3.98 (m, 1H), 6.89 (m, 2H), 7.21 (m, 2H).

Preparation Example 17(3-chloro-2-trimethylsilyloxypropyl)-(3,4-dimethoxybenzyl)amine

Yield: 93.2%;

¹H NMR (200 MHz, CDCl₃): δ 0.15 (s, 9H), 2.71 (m, 2H), 3.55 (m, 2H),3.75 (s, 2H), 3.87 (s, 3H), 3.88 (s, 3H), 3.97 (m, 1H), 6.83 (s, 2H),6.89 (s, 1H).

Preparation Example 18(3-chloro-2-trimethylsilyloxypropyl)-(4-chlorobenzyl)amine

Yield: 90.7%;

¹H NMR (200 MHz, CDCl₃): δ 0.14 (s, 9H), 2.72 (m, 2H), 3.56 (m, 2H),3.77 (s, 2H), 3.94 (m, 3H), 7.27 (m, 4H).

Preparation Example 19(3-chloro-2-trimethylsilyloxypropyl)-(4-fluorobenzyl)amine

Yield: 90.7%;

¹H NMR (200 MHz, CDCl₃): δ 0.14 (s, 9H), 2.71 (m, 2H), 3.53 (m, 2H),3.76 (s, 2H), 3.95 (m, 1H), 7.04 (m, 2H), 7.28 (m, 2H).

Preparation Example 20(3-chloro-2-trimethylsilyloxypropyl)-(3-trifluoromethylbenzyl)amine

Yield: 98%;

¹H NMR (200 MHz, CDCl₃): δ 0.15 (s, 9H), 2.78 (m, 2H), 3.58 (m, 2H),3.87 (s, 2H), 3.95 (m, 1H), 7.50 (m, 3H), 7.60 (s, 1H).

Preparation Example 21(3-chloro-2-trimethylsilyloxypropyl)-[(1R)-1-phenylethyl]amine

Yield: 97%;

¹H NMR (200 MHz, CDCl₃): δ 0.14 (s, 9H), 1.35 (d, J=6.5 Hz, 3H), 2.58(m, 2H), 3.52 (m, 2H), 3.75 (m, 1H), 3.91 (m, 1H), 7.29 (m, 5H).

Preparation Example 22(3-chloro-2-trimethylsilyloxypropyl)-[(1S)-1-phenylethyl]amine

Yield: 97%;

¹H NMR (200 MHz, CDCl₃): δ 0.14 (s, 9H), 1.35 (d, J=6.5 Hz, 3H), 2.58(m, 2H), 3.55 (m, 2H), 3.71 (m, 1H), 3.88 (m, 1H), 7.30 (m, 5H).

Preparation Example 23(3-chloro-2-trimethylsilyloxypropyl)-(4-methylbenzyl)amine

Yield: 94%;

¹H NMR (300 MHz, CDCl₃): δ 0.14 (s, 9H), 2.32 (s, 3H), 2.65˜2.79 (m,2H), 3.44˜3.59 (m, 2H), 3.74 (s, 2H), 3.94 (m, 1H), 7.10 (d, J=7.8 Hz,2H), 7.18 (d, J=7.8 Hz, 2H).

Preparation Example 24(3-chloro-2-trimethylsilyloxypropyl)-[1-(4-bromophenyl)ethyl]amine

Yield: 95% (step 2);

¹H NMR (300 MHz, CDCl₃): δ 0.15 (s, 9H), 1.31 (d, J=6.6 Hz, 3H),2.45˜2.67 (m, 2H), 3.39˜3.52 (m, 2H), 3.70 (m, J=5.1 Hz, 1H), 3.88 (m,1H), 7.19 (d, J=6.3 Hz, 2H), 7.42 (d, J=6.9 Hz, 2H).

Preparation Examples 25 to 36 Preparation of 1-substitutedbenzyl-3-trimethylsilyloxy-azetidine

Preparation Example 25 1-benzyl-3-trimethylsilyloxy-azetidine

1-Benzyl-(3-chloro-2-trimethylsilyloxy-propyl)amine (2.15 g, 7.91 mmol)prepared in Preparation Example 13 was dissolved in acetonitrile (10ml), triethylamine (1.54 g, 11.07 mmol) was added thereto, refluxed withstirring for 3 days, and cooled to room temperature. After removingsolid precipitates by filtration, the filtrate was concentrated under areduced pressure to obtain 1.8 g (yield: 96%) of the title compound.

¹H NMR (200 MHz, CDCl₃): δ 0.09 (s, 9H), 3.08 (m, 2H), 3.78 (s, 2H),3.80 (m, 2H), 4.50 (m, 1H), 7.33 (m, 5H).

The procedure of Preparation Example 25 was repeated employing each ofthe compounds of Preparation Examples 14 to 24 as a starting material toobtain the compounds of Preparation Examples 26 to 36, respectively.

Preparation Example 26 1-(4-methoxybenzyl)-3-trimethylsilyloxy-azetidine

Yield: 98.4%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 2.86 (m, 2H), 3.56 (s, 2H),3.61 (m, 2H), 3.78 (s, 3H), 4.41 (m, 1H), 6.84 (d, J=8.8 Hz, 2H) 7.17(d, J=8.8 Hz, 2H).

Preparation Example 27 1-(3-methoxybenzyl)-3-trimethylsilyloxy-azetidine

Yield: 88%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 2.98 (m, 2H), 3.61 (s, 2H),3.65 (m, 2H), 3.80 (s, 3H), 4.41 (m, 1H), 6.82 (m, 3H), 7.23 (m, 1H).

Preparation Example 28 1-(2-methoxybenzyl)-3-trimethylsilyloxy-azetidine

Yield: 89%;

¹H NMR (200 MHz, CDCl₃): δ 0.09 (s, 9H), 2.93 (m, 2H), 3.62 (s, 3H),3.81 (m, 4H), 3.78 (s, 3H), 4.41 (m, 1H), 6.83 (m, 2H), 7.21 (d, J=7.3Hz, 2H).

Preparation Example 291-(3,4-dimethoxybenzyl)-3-trimethylsilyloxy-azetidine

Yield: 85.1%;

¹H NMR (200 MHz, CDCl₃): δ 0.09 (s, 9H), 2.88 (m, 2H), 3.58 (s, 2H),3.60 (m, 2H), 3.86 (s, 3H), 3.87 (s, 3H), 4.20 (m, 1H), 6.79 (s, 2H),6.82 (s, 1H).

Preparation Example 30 1-(4-chlorobenzyl)-3-trimethylsilyloxy-azetidine

Yield: 95%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 2.82 (m, 2H), 3.57 (s, 2H),3.80 (m, 2H), 4.40 (m, 1H), 7.21 (m, 4H).

Preparation Example 31 1-(4-fluorobenzyl)-3-trimethylsilyloxy-azetidine

Yield: 90%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 2.82 (m, 2H), 3.56 (s, 2H),3.59 (m, 2H), 4.40 (m, 1H),6.97 (m, 2H), 7.23 (m, 2H).

Preparation Example 321-(3-trifluoromethylbenzyl)-3-trimethylsilyloxy-azetidine

Yield: 91%;

¹H NMR (200 MHz, CDCl₃): δ 0.09 (s, 9H), 2.90 (m, 2H), 3.61 (m, 4H),4.42 (m, 1H), 7.43 (m, 4H).

Preparation Example 331-[(1R)-1-phenylethyl]-3-trimethylsilyloxy-azetidine

Yield: 31%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 1.24 (d, J=6.5 Hz, 3H), 2.70(t, J=6.9 Hz, 1H), 2.88 (t, J=6.9 Hz, 1H), 3.29 (m, 2H), 3.78 (m, 1H),4.39 (m, 1H), 7.31 (m, 5H).

Preparation Example 341-[(1S)-1-phenylethyl]-3-trimethylsilyloxy-azetidine

Yield: 41%;

¹H NMR (200 MHz, CDCl₃): δ 0.08 (s, 9H), 1.24 (d, J=6.5 Hz, 3H), 2.70(t, J=6.9 Hz, 1H), 2.88 (t, J=6.9 Hz, 1H), 3.31 (m, 2H), 3.78 (m, 1H),4.38 (m, 1H), 7.28 (m, 5H).

Preparation Example 35 1-(4-methylbenzyl)-3-trimethylsilyloxy-azetidine

Yield: 75%;

¹H NMR (300 MHz, CDCl₃): δ 0.10 (s, 9H), 2.32 (s, 3H), 2.94 (m, 2H),3.62 (s, 2H), 3.69 (m, 2H), 4.43 (m, 1H), 7.10 (d, 2H), 7.18 (d, 2H).

Preparation Example 361-[-(4-bromophenyl)ethyl]-3-trimethylsilyloxy-azetidine

Yield: 78%;

¹H NMR (300 MHz, CDCl₃): δ 0.10 (s, 9H), 1.19 (d, J=6.6 Hz, 3H), 2.77(m, 1H), 2.86 (m, 1H), 3.25 (dd, J=6.6 Hz, J=12.9 Hz, 1H), 3.41 (m, 1H),3.66 (m, 1H), 4.41 (m, J=5.7 Hz, 1H), 7.18 (d, J=13.2 Hz, 2H), 7.44 (d,J=13.2 Hz, 2H).

Preparation Examples 37 to 48 Preparation of 1-substitutedbenzyl-azetidine-3-ol

Preparation Example 37 1-benzyl-azetidine-3-ol

1-Benzyl-3-trimethylsilyloxy-azetidine (1.8 g, 7.65 mmol) prepared inpreparation example 25 was dissolved in methanol (9 ml), sodiummethoxide (826 mg, 15.29 mmol) was added thereto, and stirred at roomtemperature for 30 min. The solvent was removed by evaporation under areduced pressure, and the residue was extracted using ethyl acetate. Theorganic extract layer was washed with water, dried over anhydrousmagnesium sulfate, and concentrated under a reduced pressure, to obtain0.964 g (yield: 77%) of the title compound.

¹H NMR (200 MHz, CDCl₃): δ 2.95 (m, 2H), 3.61 (m, 4H), 4.42 (m, 1H),7.27 (m, 5H).

The procedure of Preparation Example 37 was repeated employing each ofthe compounds of Preparation Examples 26 to 36 as a starting material toobtain the compounds of Preparation Examples 38 to 48, respectively.

Preparation Example 38 1-(4-methoxybenzyl)-azetidine-3-ol

Yield: 100%;

¹H NMR (200 MHz, CDCl₃): δ 2.91 (m, 2H), 3.53 (s, 2H), 3.57 (m, 2H),3.78 (s, 3H), 4.41 (m, 1H), 6.83 (d, J=9.0 Hz, 2H), 7.15 (d, J=8.4 Hz,2H).

Preparation Example 39 1-(3-methoxybenzyl)-azetidine-3-ol

Yield: 42%;

¹H NMR (200 MHz, CDCl₃): δ 2.99 (m, 2H), 3.60 (s, 2H), 3.63 (m, 2H),3.80 (s, 3H), 4.41 (m, 1H), 6.83 (m, 3H), 7.21 (m, 1H).

Preparation Example 40 1-(2-methoxybenzyl)-azetidine-3-ol

Yield: 53%;

¹H NMR (200 MHz, CDCl₃): δ 2.99 (m, 2H), 3.63 (s, 2H), 3.63 (m, 2H),3.80 (s, 3H), 4.39 (m, 1H), 6.87 (m, 2H), 7.26 (d, J=7.3 Hz, 2H).

Preparation Example 41 1-(3,4-dimethoxybenzyl)-azetidine-3-ol

Yield: 40%;

¹H NMR (200 MHz, CDCl₃): δ 2.91 (m, 2H), 3.54 (s, 2H), 3.58 (m, 2H),3.85 (s, 3H), 3.86 (s, 3H), 4.41 (m, 1H), 6.78 (s, 2H), 6.81 (s, 1H).

Preparation Example 42 1-(4-chlorobenzyl)-azetidine-3-ol

Yield: 66%;

¹H NMR (200 MHz, CDCl₃): δ 2.91 (m, 2H), 3.57 (s, 2H), 3.60 (m, 2H),4.41 (m, 1H), 7.22 (m, 2H).

Preparation Example 43 1-(4-fluorobenzyl)-azetidine-3-ol

Yield: 61%;

¹H NMR (200 MHz, CDCl₃): δ 2.91 (m, 2H), 3.57 (s, 2H), 3.58 (m, 2H),4.43 (m, 1H), 7.03 (m, 2H), 7.23 (m, 2H).

Preparation Example 44 1-(3-trifluoromethylbenzyl)-azetidine-3-ol

Yield: 64%;

¹H NMR (200 MHz, CDCl₃): δ 2.98 (m, 2H), 3.69 (m, 4H), 4.49 (m, 1H),7.44 (m, 4H).

Preparation Example 45 1-[(1R)-1-phenylethyl]-azetidine-3-ol

Yield: 59%;

¹H NMR (200 MHz, CDCl₃): 1.25 (d, J=6.5 Hz, 3H), 2.90 (m, 2H), 3.38 (m,2H), 3.70 (m, 1H), 4.40 (m, 1H), 4.78 (bs, 1H), 7.27 (m, 5H).

Preparation Example 46 1-[(1S)-1-phenylethyl]-azetidine-3-ol

Yield: 63%;

¹H NMR (200 MHz, CDCl₃): 1.25 (d, J=6.5 Hz, 3H), 2.90 (m, 2H), 3.38 (m,2H), 3.71 (m, 1H), 4.40 (m, 1H), 4.50 (bs, 1H), 7.27 (m, 5H).

Preparation Example 47 1-(4-methylbenzyl)-azetidine-3-ol

Yield: 65%;

¹H NMR (300 MHz, CDCl₃): δ 2.32 (s, 3H), 2.92 (m, 2H), 3.53 (m, 4H),4.38 (m, 1H), 7.09 (s, 4H).

Preparation Example 48 1-[1-(4-bromophenyl)ethyl]-azetidine-3-ol

Yield: 61%;

¹H NMR (300 MHz, CDCl₃): δ 1.19 (d, J=6.6 Hz, 3H), 2.76 (m, 1H), 2.88(m, 1H), 3.24 (dd, J=6.6 Hz, J=12.9 Hz, 1H), 3.37 (m, 1H), 3.69 (m, 1H),4.40 (m, J=5.7 Hz, 1H), 7.15 (d, J=13.2 Hz, 2H), 7.41 (d, J=13.2 Hz,2H).

Preparation Examples 49 to 60 Preparation of 1-substitutedbenzyl-3-acetylthio-azetidine

Preparation Example 49 1-benzyl-3-acetylthio-azetidine

Triphenylphosphine (3.08 g, 11.76 mmol) was dissolved in anhydroustetrahydrofuran (THF) (30 ml). Oxygen was completely removed by passingnitrogen through the mixture, and the mixture was cooled to 0° C.Diisopropylazodicarboxylate (2.3 ml, 11.76 mmol) was added thereto, andstirred at 0° C. for 1 hour. Added slowly to the mixture in successionwere thioacetic acid (840 μl, 11.76 mmol) and 1-benzyl-azetidine-3-ol(960 mg, 5.88 mmol) prepared in Preparation Example 37 and dissolved intetrahydrofuran (20 ml). The resulting solution was heated to roomtemperature, stirred for 2 hours and concentrated under a reducedpressure to remove the solvent. The concentrate was dissolved in ethylacetate, washed with water, dried over anhydrous magnesium sulfate andconcentrated under a reduced pressure. The resulting residue waspurified by column chromatography (eluent−ethyl acetate/normalhexane=1/1) to obtain 1.1 g (yield: 83%) of the title compound.

¹H NMR (200 MHz, CDCl₃): 2.31 (s, 3H), 3.10 (m, 2H), 3.61 (s, 2H), 3.70(m, 2H), 4.15 (m, 1H), 7.26 (m, 5H).

The procedure of Preparation Example 49 was repeated employing each ofthe compounds of Preparation Examples 38 to 48 as a starting material toobtain the compounds of Preparation Examples 50 to 60, respectively.

Preparation Example 50 1-(4-methoxybenzyl)-3-acetylthio-azetidine

Yield: 83%;

¹H NMR (200 MHz, CDCl₃): 2.27 (s, 3H), 3.05 (m, 2H), 3.53 (s, 2H), 3.66(m, 2H), 3.77 (s, 3H), 4.12 (m, 1H), 6.81 (d, J=8.8 Hz, 2H), 7.17 (d,J=8.8 Hz, 2H).

Preparation Example 51 1-(3-methoxybenzyl)-3-acetylthio-azetidine

Yield: 100%;

¹H NMR (200 MHz, CDCl₃): 2.29 (s, 3H), 3.08 (m, 2H), 3.59 (s, 2H), 3.71(m, 2H), 3.80 (s, 3H), 4.15 (m, 1H), 6.81 (m, 3H), 7.21 (m, 1H).

Preparation Example 52 1-(2-methoxybenzyl)-3-acetylthio-azetidine

Yield: 33%;

¹H NMR (200 MHz, CDCl₃): 2.29 (s, 3H), 3.12 (m, 2H), 3.64 (s, 2H), 3.76(m, 2H), 3.81 (s, 3H), 4.18 (m, 1H), 6.89 (m, 2H), 7.26 (d, J=7.5 Hz,2H).

Preparation Example 53 1-(3,4-dimethoxybenzyl)-3-acetylthio-azetidine

Yield: 59%;

¹H NMR (200 MHz, CDCl₃): 2.29 (s, 3H), 3.07 (m, 2H), 3.55 (s, 2H), 3.69(m, 2H), 3.85 (s, 3H), 3.88 (s, 3H), 4.18 (m, 1H), 6.78 (s, 2H), 6.81(s, 1H).

Preparation Example 54 1-(4-chlorobenzyl)-3-acetylthio-azetidine

Yield: 88%;

¹H NMR (200 MHz, CDCl₃): 2.29 (s, 3H), 3.08 (m, 2H), 3.57 (s, 2H), 3.68(m, 2H), 4.13 (m, 1H), 7.21 (m, 4H).

Preparation Example 55 1-(4-fluorobenzyl)-3-acetylthio-azetidine

Yield: 30.7%;

¹H NMR (200 MHz, CDCl₃): 2.30 (s, 3H), 3.11 (m, 2H), 3.60 (s, 2H), 3.71(m, 2H), 4.14 (m, 1H), 7.03 (m, 2H), 7.22 (m, 2H).

Preparation Example 561-(3-trifluoromethylbenzyl)-3-acetylthio-azetidine

Yield: 20%;

¹H NMR (200 MHz, CDCl₃): 2.30 (s, 3H), 3.11 (m, 2H), 3.67 (s, 2H), 3.72(m, 2H), 4.18 (m, 1H), 7.49 (m, 4H).

Preparation Example 57 1-[(1R)-1-phenylethyl]-3-acetylthio-azetidine

Yield: 20%;

¹H NMR (200 MHz, CDCl₃): 1.21 (d, J=6.5 Hz, 3H), 2.28 (s, 3H), 2.99 (t,J=7.3 Hz, 2H), 3.29 (q, J=6.5 Hz, 1H), 3.52 (t, J=7.3 Hz, 1H), 3.72 (t,J=7.3 Hz, 1H), 4.09 (qint, J=6.5 Hz, 1H), 7.25 (m, 5H).

Preparation Example 58 1-[(1S)-1-phenylethyl]-3-acetylthio-azetidine

Yield: 20%;

¹H NMR (200 MHz, CDCl₃): 1.20 (d, J=6.5 Hz, 3H), 2.28 (s, 3H), 2.99 (t,J=7.3 Hz, 2H), 3.29 (q, J=6.5 Hz, 1H), 3.52 (t, J=7.3 Hz, 1H), 3.72 (t,J=7.3 Hz, 1H), 4.09 (qint, J=6.9 Hz, 1H), 7.27 (m, 5H).

Preparation Example 59 1-(4-methylbenzyl)-3-acetylthio-azetidine

Yield: 54%;

¹H NMR (300 MHz, CDCl₃): δ 2.32 (s, 3H), 2.59 (s, 3H), 3.08 (m, 2H),3.58 (s, 2H), 3.69 (m, 2H), 4.12 (m, 1H), 7.10 (d, 4H).

Preparation Example 60 1-[1-(4-bromophenyl)ethyl]-3-acetylthio-azetidine

Yield: 69%;

¹H NMR (300 MHz, CDCl₃): δ 1.18 (d, J=6.6 Hz, 3H), 2.28 (s, 3H), 2.98(br, 2H), 3.26 (dd, J=6.6 Hz, J=12.9 Hz, 1H), 3.50 (t, 1H), 3.68 (t,1H), 4.08 (m, J=5.7 Hz, 1H), 7.15 (d, J=13.2 Hz, 2H), 7.39 (d, J=13.2Hz, 2H).

Preparation Examples 61 to 72 Preparation of 1-substitutedbenzyl-azetidine-3-thiol

Preparation Example 61 1-benzyl-azetidine-3-thiol

1-Benzyl-3-acetylthio-azetidine (1 g, 4.518 mmol) prepared inPreparation Example 49 was dissolved in methanol (20 ml), and oxygen wascompletely removed by passing nitrogen through the mixture. Theresulting mixture was cooled to 0° C., 2N sodium hydroxide (2.27 ml,4.518 mmol) was added thereto slowly, stirred at 0° C. for 30 min, andthen 2N—HCl was added thereto to neutralize (pH 7) the mixture. Theresulting solution was concentrated under a reduced pressure, and theconcentrate was dissolved in ethyl acetate, and washed with a saturatedsalt solution. The organic layer was dried over magnesium sulfate andconcentrated under a reduced pressure to obtain 620 mg (yield: 77%) ofthe title compound, which was used in the next reaction without anyadditional purification.

The procedure of Preparation Example 61 was repeated employing each ofthe compounds of Preparation Examples 50 to 60 as a starting material toobtain the compounds of Preparation Examples 62 to 72, respectively.

Preparation Example 62 1-(4-methoxybenzyl)-azetidine-3-thiol

Yield: 93%.

Preparation Example 63 1-(3-methoxybenzyl)-azetidine-3-thiol

Yield: 100%.

Preparation Example 64 1-(2-methoxybenzyl)-azetidine-3-thiol

Yield: 83%.

Preparation Example 65 1-(3,4-dimethoxybenzyl)-azetidine-3-thiol

Yield: 100%.

Preparation Example 66 1-(4-chlorobenzyl)-azetidine-3-thiol

Yield: 80%.

Preparation Example 67 1-(4-fluorobenzyl)-azetidine-3-thiol

Yield: 98%.

Preparation Example 68 1-(3-trifluoromethylbenzyl)-azetidine-3-thiol

Yield: 90%.

Preparation Example 69 1-[(1R)-1-phenylethyl]-azetidine-3-thiol

Yield: 99%.

Preparation Example 70 1-[(1S)-1-phenylethyl]-azetidine-3-thiol

Yield: 67%.

Preparation Example 71 1-(4-methylbenzyl)-azetidine-3-thiol

Yield: 80%.

Preparation Example 72 1-[1-(4-bromophenyl)ethyl]-azetidine-3-thiol

Yield: 88%.

Examples 1 to 12 4-nitrobenzyl(1R,5S,6S)-2-(1-substitutedbenzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Example 14-nitrobenzyl(1R,5S,6S)-2-(1-benzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

1-benzyl-azetidine-3-thiol (620 mg, 3.46 mmol) prepared in PreparationExample 61 was dissolved in acetonitrile (20 ml), and the mixture wascooled to a temperature raging from −20 to −10° C. Added to the mixturewere diisopropylethylamine (733 μl, 4.21 mmol) and4-nitrobenzyl(1R,5S,6S)-2-(diphenylphosphoryloxy)-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-estercarboxylate (2.09 g, 3.51 mmol) under a nitrogen atmosphere, and theresulting mixture was stirred at a temperature ranging from −20 to −10°C. for 2 hours. The resulting solution was extracted with ethyl acetate,the extract was washed with water then with a saturated salt solution,dried over anhydrous magnesium sulfate and concentrated under a reducedpressure. The concentrate was subjected to column chromatography(eluent−ethyl acetate/methanol=10/1) to obtain 720 mg (yield: 40%) ofthe title compound.

¹H NMR (200 MHz, CDCl₃) δ 1.21 (d, J=7.3 Hz, 3H), 1.36 (d, J=6.1 Hz,3H), 3.12 (m, 2H), 3.22 (m, 2H), 3.63 (s, 2H), 3.77 (m, 2H), 3.97 (m,1H), 4.20 (m, 2H), 5.36 (q, J=13.8 Hz, 53.3 Hz, 2H), 7.28 (m, 5H), 7.67(d, J=8.9 Hz, 2H), 8.23 (d, J=8.9 Hz, 2H).

The procedure of Example 1 was repeated to obtain the compounds ofExamples 2 to 12 employing each of the compounds of Preparation Examples62 to 72 as a starting material.

Example 24-nitrobenzyl(1R,5S,6S)-2-[1-(4-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 32%;

¹H NMR (200 MHz, CDCl₃): δ 1.20 (d, J=7.3 Hz, 3H), 1.34 (d, J=6.1 Hz,3H), 3.10 (m, 2H), 3.24 (m, 2H), 3.55 (s, 2H), 3.69 (m, 2H), 3.78 (s,3H), 3.92 (m, 1H), 4.19 (m, 2H), 5.36 (q, J=13.8 Hz, 53.3 Hz, 2H), 6.84(d, J=8.5 Hz, 2H), 7.16 (d, J=8.5 Hz, 2H), 7.65 (d, J=8.7 Hz, 2H), 8.22(d, J=8.7 Hz, 2H).

Example 34-nitrobenzyl(1R,5S,6S)-2-[1-(3-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 34%;

¹H NMR (200 MHz, CDCl₃): δ 1.20 (d, J=6.9 Hz, 3H), 1.37 (d, J=6.1 Hz,3H), 3.14 (m, 2H), 3.22 (m, 2H), 3.60 (s, 2H), 3.75 (m, 2H), 3.80 (s,3H), 3.97 (m, 1H), 4.21 (m, 2H), 5.38 (q, J=13.8 Hz, 52.9 Hz, 2H), 6.80(m, 3H), 7.21 (m, 1H), 7.67 (d, J=8.5 Hz, 2H), 8.24 (d, J=8.5 Hz, 2H).

Example 44-nitrobenzyl(1R,5S,6S)-2-[1-(2-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 42%;

¹H NMR (200 MHz, CDCl₃): δ 1.21 (d, J=7.3 Hz, 3H), 1.36 (d, J=6.1 Hz,3H), 3.21 (m, 4H), 3.65 (s, 2H), 3.81 (m, 6H), 4.01 (m, 1H), 6.88 (m,2H), 7.21 (m, 2H), 7.67 (d, J=8.3 Hz, 2H), 8.23 (d, J=8.1 Hz, 2H).

Example 54-nitrobenzyl(1R,5S,6S)-2-[1-(3,4-dimethoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 27%;

¹H NMR (200 MHz, CDCl₃): δ 1.21 (d, J=7.3 Hz, 3H), 1.35 (d, J=6.3 Hz,3H), 3.08 (m, 2H), 3.22 (m, 2H), 3.56 (s, 2H), 3.74 (m, 2H), 3.85 (s,3H), 3.87 (s, 3H), 3.99 (m, 1H), 4.20 (m, 2H), 5.38 (q, J=13.8 Hz, 53.5Hz, 2H), 6.78 (s, 3H), 7.66 (d, J=9.0 Hz, 2H), 8.22 (d, J=8.8 Hz, 2H).

Example 64-nitrobenzyl(1R,5S,6S)-2-[1-(4-chlorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 12%;

¹H NMR (200 MHz, CDCl₃): δ 1.22 (d, J=7.5 Hz, 3H), 1.36 (d, J=6.3 Hz,3H), 3.11 (m, 2H), 3.25 (m, 2H), 3.58 (s, 2H), 3.72 (m, 2H), 3.95 (m,1H), 4.20 (m, 2H), 5.35 (q, J=13.6 HZ, 54.1 Hz, 2H), 7.21 (m, 4H), 7.64(m, 2H), 8.21 (d, J=8.7 Hz, 2H).

Example 74-nitrobenzyl(1R,5S,6S)-2-[1-(4-fluorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 56%;

¹H NMR (200 MHz, CDCl₃): δ 1.19 (d, J=7.1 Hz, 3H), 1.34 (d, J=6.1 Hz,3H), 3.07 (m, 2H), 3.21 (m, 2H), 3.57 (s, 2H), 3.73 (m, 2H), 3.95 (m,1H), 4.21 (m, 2H), 5.38 (q, J=13.8 HZ, 53.7 Hz, 2H), 6.98 (m, 2H), 7.19(m, 2H), 7.65 (d, J=9.0 Hz, 2H), 8.22 (d, J=9.0 Hz, 2H).

Example 84-nitrobenzyl(1R,5S,6S)-2-[1-(3-trifluoromethylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 36%;

¹H NMR (200 MHz, CDCl₃): δ 1.23 (d, J=7.3 Hz, 3H), 1.37 (d, J=6.5 Hz,3H), 3.17 (m, 2H), 3.22 (m, 2H), 3.68 (s, 2H), 3.74 (m, 2H), 4.00 (m,1H), 4.21 (m, 2H), 5.49 (q, J=13.8 HZ, 53.7 Hz, 2H), 7.51 (m, 4H), 7.67(d, J=8.9 Hz, 2H), 8.25 (d, J=9.0 Hz, 2H).

Example 94-nitrobenzyl(1R,5S,6S)-2-{1-[(1S)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 36%;

¹H NMR (200 MHz, CDCl₃): δ 1.20 (d, J=7.3 Hz, 3H), 1.22 (J=6.1 Hz, 3H),1.35 (d, J=6.5 Hz, 3H), 2.96 (t, J=7.1 Hz, 1H), 3.09 (t, 6.7 Hz, 1H),3.22 (m, 2H), 3.31 (m, 1H), 3.47 (m, 1H), 3.88 (m, 2H), 4.09 (m, 3H),5.38 (q, J=13.8 HZ, 54.3 Hz, 2H), 7.25 (m, 5H), 7.66 (d, J=9.0 Hz, 2H),8.23 (d, J=9.0 Hz, 2H).

Example 104-nitrobenzyl(1R,5S,6S)-2-{1-[(1S)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 25%;

¹H NMR (200 MHz, CDCl₃): δ 1.20 (d, J=7.3 Hz, 3H), 1.22 (J=6.2 Hz, 3H),1.35 (d, J=6.5 Hz, 3H), 3.01 (m, 2H), 3.31 (m, 3H), 3.50 (m, 1H), 3.82(m, 2H), 4.21 (m, 2H), 4.21 (m, 3H), 5.38 (q, J=13.8 HZ, 78.0 Hz, 2H),7.67 (d, J=8.7 Hz, 2H), 8.23 (d, J=8.7 Hz, 2H).

Example 114-nitrobenzyl(1R,5S,6S)-2-[1-(4-methylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 35%;

¹H NMR (200 MHz, CDCl₃): δ 1.21 (d, J=7.3 Hz, 3H), 1.35 (d, J=6.5 Hz,3H), 2.32 (s, 3H), 3.11 (q, J=7.3 Hz, 2H), 3.22 (m, 2H), 3.58 (s, 2H),3.78 (m, 2H), 3.98 (m, 1H), 4.18 (m, 2H), 5.39 (q, J=13.8 HZ, 52.9 Hz,2H), 7.12 (s, 4H), 7.66 (d, J=8.5 Hz, 2H), 8.23 (d, J=9.0 Hz, 2H).

Example 124-nitrobenzyl(1R,5S,6S)-2-{1-[1-(4-bromophenyl)ethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-estercarboxylate

Yield: 43%;

¹H NMR (200 MHz, CDCl₃): δ 1.21 (m, 6H), 1.36 (d, J=6.5 Hz, 3H), 2.98(m, 3H), 3.11 (q, J=7.3 Hz, 2H), 3.22 (m, 2H), 3.58 (s, 2H), 3.78 (m,2H), 3.98 (m, 1H), 3.05 (m, 1H), 3.23 (m, 3H), 3.44 (m, 1H), 3.81 (m,2H), 4.20 (m, 2H), 5.37 (q, J=13.4 HZ, 53.3 Hz, 2H), 7.16 (d, J=8.1 Hz,2H), 7.44 (d, J=8.5 Hz, 2H), 7.66 (d, J=9.0 Hz, 2H), 8.23 (d, J=8.5 Hz,2H).

Examples 13 to 24 Potassium(1R,5S,6S)-2-(1-substitutedbenzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Example 13Potassium(1R,5S,6S)-2-(1-benzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

4-Nitrobenzyl(1R,5S,6S)-2-(1-benzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-estercarboxylate (70 mg, 0.133 mmol) prepared in Example 1 was dissolved inTHF (2 ml) and added thereto were potassium phosphate buffer (pH 7, 2ml) and 10% palladium/carbon (20 mg) as a catalyst. The mixture wasstirred under a hydrogen atmosphere (employing hydrogen balloon) at roomtemperature for 3 hours. The catalyst was removed by filtration, and thefiltrate was concentrated under a reduced pressure. A small amount ofwater was added to the residue, and washed with ethyl carboxylate toremove impurities. The aqueous layer was subjected to C18 reverse phasecolumn MPLC (eluent-water and 10% acetonitrile aqueous solution), andthe product was collected and lyophilized to obtain 14 mg (yield: 27%)of the title compound.

¹H NMR (300 MHz, D₂O): δ 0.98 (d, J=6.9 Hz, 3H), 1.12 (d, J=6.1 Hz, 3H),3.01 (m, 1H), 3.22 (m, 1H), 3.73 (m, 2H), 4.02 (m, 3H), 4.10 (s, 2H),4.17 (m, 2H), 7.16 (m, 5H).

The procedure of Example 13 was repeated to obtain the compounds ofExamples 14 to 24 employing each of the compounds prepared in Examples 2to 12 as a starting material.

Example 14Potassium(1R,5S,6S)-2-[1-(4-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 24%;

¹H NMR (300 MHz, D₂O): δ 1.07 (d, J=7.2 Hz, 3H), 1.21 (d, J=6.3 Hz, 3H),3.08 (m, 1H), 3.35 (m, 1H), 3.77 (s, 2H), 3.86 (m, 3H), 4.07 (m, 2H),4.18 (s, 3H), 4.33 (m, 2H), 7.33 (d, J=8.6 Hz, 2H).

Example 15Potassium(1R,5S,6S)-2-[1-(3-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 15%;

¹H NMR (300 MHz, D₂O): δ 0.99 (d, J=6.9 Hz, 3H), 1.13 (d, J=6.5 Hz, 3H),3.00 (m, 1H), 3.23 (m, 1H), 3.69 (s, 3H), 3.81 (m, 2H), 4.08 (m, 3H),4.16 (s, 2H), 4.29 (m, 2H), 6.89 (m, 3H), 7.26 (m, 1H).

Example 16Potassium(1R,5S,6S)-2-[1-(2-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 32%;

¹H NMR (300 MHz, D₂O): δ 0.84 (d, J=7.1 Hz, 3H), 0.99 (d, J=6.3 Hz, 3H),2.90 (m, 1H), 3.10 (m, 1H), 3.19 (m, 2H), 3.56 (s, 3H), 3.62 (s, 2H),3.72 (m, 3H), 3.86 (d, J=7.4 Hz, 1H), 3.92 (t, J=6.2 Hz, 1H), 6.76 (m,2H), 7.00 (d, J=7.4 Hz, 1H), 7.11 (t, J=8.3 Hz, 1H).

Example 17Potassium(1R,5S,6S)-2-[1-(3,4-dimethoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 24%;

¹H NMR (300 MHz, D₂O): δ 0.99 (d, J=7.3 Hz, 3H), 1.13 (d, J=6.1 Hz, 3H),3.63 (m, 2H), 3.71 (s, 6H), 3.98 (s, 2H), 4.04 (m, 5H), 6.87 (bs, 3H).

Example 18Potassium(1R,5S,6S)-2-[1-(4-chlorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 11%;

¹H NMR (300 MHz, D₂O): δ 0.99 (d, J=6.9 Hz, 3H), 1.15 (d, J=6.5 Hz, 3H),3.08 (m, 3H), 3.21 (m, 1H), 3.53 (s, 2H), 3.58 (m, 2H), 3.80 (m, 1H),4.01 (m, 1H), 7.14 (d, J=8.1 Hz, 2H), 7.27 (d, J=8.1 Hz, 2H).

Example 19Potassium(1R,5S,6S)-2-[1-(4-fluorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 36%;

¹H NMR (300 MHz, D₂O): δ 1.17 (d, J=7.3 Hz, 3H), 1.31 (d, J=6.1 Hz, 3H),3.20 (m, 1H), 3.41 (m, 1H), 3.69 (m, 2H), 4.07 (s, 2H), 4.18 (m, 5H),7.20 (m, 2H), 7.40 (m, 2H).

Example 20Potassium(1R,5S,6S)-2-[1-(3-trifluoromethylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 58%;

¹H NMR (300 MHz, D₂O): δ 0.99 (d, J=6.9 Hz, 3H), 1.14 (d, J=6.5 Hz, 3H),3.16 (m, 2H), 3.21 (m, 2H), 3.65 (m, 4H), 3.82 (m, 1H), 4.00 (m, 1H),4.08 (m, 1H), 7.40 (m, 2H), 7.53 (m, 2H).

Example 21Potassium(1R,5S,6S)-2-{1-[(1R)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 58%;

¹H NMR (300 MHz, D₂O): δ 0.83 (d, J=7.2 Hz, 3H), 0.98 (d, J=6.3 Hz, 3H),1.12 (d, J=6.5 Hz, 3H), 2.87 (t, J=7.4 Hz, 1H), 3.11 (m, 1H), 3.32 (m,2H), 3.85 (m, 6H), 7.15 (m, 5H).

Example 22Potassium(1R,5S,6S)-2-{1-[(1S)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 49%;

¹H NMR (300 MHz, D₂O): δ 0.83 (d, J=7.2 Hz, 3H), 0.98 (d, J=6.3 Hz, 3H),1.12 (d, J=6.5 Hz, 3H), 2.87 (t, J=7.4 Hz, 1H), 3.11 (m, 1H), 3.32 (m,2H), 3.85 (m, 6H), 7.15 (m, 5H).

Example 23Potassium(1R,5S,6S)-2-[1-(4-methylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 29%;

¹H NMR (300 MHz, D₂O): δ 0.99 (d, J=6.9 Hz, 3H), 1.13 (d, J=6.1 Hz, 3H),2.18 (s, 3H), 3.04 (t, J=7.2 Hz, 1H), 3.23 (m, 1H), 3.61 (m, 2H), 4.01(m, 7H), 7.13 (m, 4H).

Example 24Potassium(1R,5S,6S)-2-{1-[1-(4-bromophenyl)ethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxylethyl]-1-methylcarbapen-2-em-3-carboxylate

Yield: 43%;

¹H NMR (300 MHz, D₂O): δ 0.84 (d, J=7.2 Hz, 3H), 1.16 (d, J=6.3 Hz, 3H),1.18 (d, J=6.5 Hz, 3H), 2.98 (m, 2H), 3.17 (m, 1H), 3.43 (m, 2H), 3.72(m, 2H), 3.91 (m, 2H), 4.08 (m, 1H), 7.04 (d, J=8.1 Hz, 2H), 7.28 (d,J=8.1 Hz, 2H).

Test Example 1 Measurement of Minimum Inhibitory Concentration (MIC)

The antibacterial activities of the compounds of the present inventionprepared in the above Examples against Gram-positive and Gram-negativebacteria, MRSA and QRS were tested as follows.

Respective bacterial strains were inoculated into 3 ml of Fleischextract broth (beef extract 1%, peptone 1%, NaCl 0.3%, Na₂HPO₄.12H₂O0.2%, pH 7.4-7.5. 10% horse serum was supplemented for Streptococcuspyogenes and S. facium) and cultured on a shaking incubator at 37° C.for 18 hours. About 10⁴ CFU/spot of the cultured bacterial strains wereinoculated onto Müller-Hinton agar plates containing serial doubledilutions (final concentration of 0.002 to 100 μg/ml) of a test compoundemploying an automatic inoculator (Dynatech, USA), and incubated at 37°C. for 18 hours. When the incubation was completed, the minimuminhibitory concentration was determined. The results are shown in Table1 and Table 2. Meropenem (Yuhan corporation, Korea) and vancomycin (CjInco., Korea) were used as standard antibiotics, respectively.

TABLE 1 MIC (μg/ml) Exam. Exam. Exam. Exam. Exam. Exam. strains 13 14 1617 19 22 meropenem vancomycin Staphylococcus 0.002 0.002 0.002 0.0020.002 0.002 0.007 0.781 pyogenes 308A Staphylococcus 0.002 0.002 0.0020.002 0.002 0.002 0.004 0.391 pyogenes 77A Staphylococcus 1.563 1.5631.563 1.563 1.563 1.563 6.250 0.391 faecium MD 8b Staphylococcus 0.0250.098 0.025 0.025 0.025 0.025 0.098 0.391 aureus 285 Staphylococcus0.013 0.025 0.013 0.013 0.013 0.013 0.049 0.391 aureus 503 Escherichiacoli 0.049 0.013 0.098 0.098 0.025 0.098 0.025 100.00 078 Escherichiacoli 0.098 0.049 0.781 0.781 0.098 0.391 0.025 100.00 DC 0 Escherichiacoli 0.025 0.049 0.049 0.049 0.025 0.025 0.025 50.000 DC 2 Escherichiacoli 0.049 0.195 0.195 0.391 0.049 0.391 0.025 100.00 TEM Escherichiacoli 0.049 0.098 0.195 0.391 0.049 0.195 0.025 100.00 1507 E Salmonella0.049 0.098 0.098 0.098 0.049 0.049 0.049 100.00 typhimurium 179Klebsiella oxytoca 0.049 0.098 0.098 0.098 0.049 0.098 0.049 100.00 1082E Klebsiella 0.098 0.195 0.391 0.391 0.098 0.391 0.049 100.00 aerogenes1522 E Enterobacter 0.098 0.391 0.391 0.781 0.098 0.391 0.049 100.00cloacae P 99 Enterobacter 0.049 0.098 0.098 0.391 0.049 0.098 0.025100.00 cloacae 1321 E

TABLE 2 MIC (μg/ml) Exam. Exam. Exam. Exam. Exam. Exam. strain 13 14 1617 19 22 Meropenem Vancomycin MRSA Staphylococcus 0.025 0.1951 0.0250.195 0.049 0.025 0.195 0.781 aureus 88E Staphylococcus 0.025 0.0980.025 0.098 0.049 0.049 0.195 0.781 aureus 121E Staphylococcus 0.0490.049 0.025 0.049 0.025 0.025 0.098 0.781 aureus 208E Staphylococcus0.013 0.025 0.025 0.049 0.025 0.025 0.049 0.781 aureus 256EStaphylococcus 0.391 0.391 0.195 0.781 0.391 0.195 3.125 0.391 aureus690E Staphylococcus 0.025 0.391 0.049 0.195 0.025 0.025 0.098 0.781aureus 692E Staphylococcus 3.125 0.391 1.563 0.391 3.125 3.125 6.2501.563 aureus 693E Staphylococcus 1.563 0.098 0.049 0.098 3.125 0.0496.250 1.563 aureus 694E Staphylococcus 0.391 0.098 0.049 0.098 0.1950.098 0.781 1.563 aureus 695E Staphylococcus 0.025 0.195 0.025 0.0980.049 0.025 0.098 0.781 aureus 697E QRS Staphylococcus 0.049 0.049 0.0490.098 0.049 0.049 0.195 0.781 aureus 179 Staphylococcus 0.049 0.0490.025 0.195 0.049 0.049 0.195 0.781 aureus 241 Staphylococcus 0.0980.098 0.098 0.391 0.195 0.195 0.781 0.781 aureus 293 Staphylococcus0.391 0.391 0.195 0.781 0.195 0.195 0.781 1.563 epidermidis 178Staphylococcus 0.391 0.391 0.391 1.563 0.391 0.391 1.563 1.563epidermidis 291

As can be seen in Tables 1 and 2, the carbapenem derivatives of thepresent invention exhibited superior antibacterial activities againststandard strains of Gram-positive and Gram-negative bacteria and alsoagainst MRSA and QRS as resistant strains over the standard antibiotics(meropenem and vancomycin).

Test Example 2 Test of Pharmacokinetics in Animals

The pharmacokinetics of the carbapenem derivatives of the presentinvention was determined using mice. Each of the compounds of Examples13 and 14 and meropenem (a positive control) was dissolved in distilledwater, and mice were orally administered (PO) or subcutaneously injected(SC) at a dosage of 40 mg/kg body weight (I.C.R mice, weighing 22 to 25g, 4 mice/group). Blood samples were withdrawn from mice tails usingheparinated capillaries at 10 min., 20 min., 30 min., 45 min., 1 hour, 2hours, 3 hours and 4 hours after the administration.

Standard antibiotic samples were prepared by serial two-fold dilutionwith control blood. Agar plates were prepared with Müller-Hinton agarmedium containing 6.7% sheep blood and 1% Streptococcus pyogenes 77Aculture solution, and the diluted standard and blood samples were addedto wells formed on the plates. The plate was stored at 4° C. for 1 hourto allow the sample to spread, and incubated at 37° C. for 18 hours. PK(pharmacokinetic) change indicators (AUC, T_(max), C_(max) and T_(1/2))of the test compound concentration remaining in the mouse blood overtime were assayed over a set period. The result is shown in Table 3.

TABLE 3 Adminis- AUC*¹ C_(max)*³ medicament tration (μg · h/ml)T_(max)*² (hr) (μg/ml) T_(1/2)*⁴ (hr) Exam. 13 SC 94.76 0.22 86.83 0.92PO 1.73 0.49 1.06 0.81 Exam. 14 SC 79.66 0.25 69.61 0.76 PO 5.20 0.442.07 2.06 Meropenem SC 7.50 0.33 13.39 0.43 PO N.D N.D N.D N.D *¹areaunder blood-medicament concentration curve till 24 hours fromadministration *²time at the point of maximum blood-medicamentconcentration *³maximum blood-medicament concentration *⁴half time ofblood-medicament concentration N.D: Not detected

As can be seen in Table 3, the compounds of Example 13 and 14 showed 10to 12 times higher AUC and a more than 2 times increase in T_(1/2) thanmeropenem, and unlike meropenem, the compounds of Example 13 and 14 wereabsorbed through the oral route to significant extents. Thus, thecompounds of the present invention exhibit excellent pharmacokinetics.

Then, pharmacokinetical assay (amount of medicament administered was 20mg/kg) was carried out as above using rats.

TABLE 4 Adminis- AUC*¹ C_(max)*³ medicament tration (μg · h/ml)T_(max)*² (hr) (μg/ml) T_(1/2)*⁴ (hr) Exam. 14 SC 34.58 0.37 35.85 0.69PO 0.33 0.71 0.20 5.07 Meropenem SC 2.05 0.25 3.92 0.31 PO N.D N.D N.DN.D *¹area under blood-medicament concentration curve till 24 hoursafter administration *²time at the point of maximum blood-medicamentconcentration *³maximum blood-medicament concentration *⁴half time ofblood-medicament concentration N.D: not detected

As can be seen in Table 4, in rats, the compound of Example 14 showed 17times higher AUC and a more than 2 times increase in T_(1/2) thanmeropenem, and unlike meropenem, the compound of Example 14 was absorbedthrough the oral route to a significant extent. Thus, the compound ofthe present invention exerted equally good pharmacokinetic profiles inrats.

Test Example 3 Determination of Protection Dose (PD₅₀) in InfectedAnimal Model

In order to get the lethal dose (LD₁₀₀) of bacteria, Staphylococcuspyogenes 77A and Escherichia coli 078 were each diluted by 10²˜10⁹times. The CFU (colony forming unit) of each bacterial solution wascalculated, and the diluted bacterial solution was intraperitoneallyadministered to mice and the death was observed for 7 days. For a mainexperiment, 3 to 4 week-old SPF ICR male mice were divided into 4 groupseach of 8 to 10 mice, and fasted for 24 hours before a test. Thesolutions of Staphylococcus pyogenes 77A and Escherichia coli 078 wereconcentrated to a level that was 2 to 10 times of LD₁₀₀, and theconcentrated Staphylococcus pyogenes 77A solution mixed with 10% horseserum and the concentrated Escherichia coli 078 solution mixed with 5%hog gastric mucin were each injected intraperitoneally into the mice ofeach group to induce whole body infection.

The serially diluted solutions of the compound of Example 14 ormeropenem (5 different concentrations) were injected intraperitoneallyinto the infected mice 1 hour after the infection. All of the mice inthe control group injected with physiological salt solution died within48 hours. The number of survived mouse in each group injected withantibacterial material, were counted to determine PD₅₀, and the 95%confidence interval thereof was calculated employing Probit method. Theresult is shown in Table 5.

TABLE 5 Staphylococcus pyogenes 77A Escherichia coli 078 Exam. 14 3.051.44 (2.19-4.45) (0.83-2.27) Meropenem 9.13 3.31  (7.5-15.0) (2.03-5.40)unit: mg/kg ( ): 95% confidence interval

As can be seen in Table 5, the compound of Example 14 provided higherefficacy against Staphylococcus pyogenes or Escherichia coli thanmeropenem.

Test Example 4 Sensitivity Assay Against Dihydropeptidase-1 (DHP-1)

The rate of degradation of the inventive compounds by the action ofDHP-1 enzyme extracted from hog kidney was determined as follow.

0.3 mg of the compounds of Example 13 to 24 (test materials), meropenemand imipenem (Choongwae pharma. Corp., control materials) were dissolvedin 50 mM MOPS buffer to a concentration of 500 μg/ml. 0.2 unit of theenzyme was allowed to react with the above solution at 30° C., and theabsorbance at 299 nm of the remaining medicament was measured todetermine the degradation rate. The absorbance was measured at 0, 0.5,1, 2 and 4 hour points, and T_(1/2), the time when the concentration ofthe medicament become the half, was obtained by regression analysis.Relative T_(1/2) was calculated based on T_(1/2)=1.0 for meropenem. Theresult is shown in Table 6.

TABLE 6 medicament T_(1/2) Relative T_(1/2) Exam. 13 19.28 1.10 Exam. 1419.88 1.13 Exam. 15 28.16 1.54 Exam. 16 200.91 9.81 Exam. 17 27.45 1.54Exam. 18 15.36 0.84 Exam. 19 28.16 1.54 Exam. 20 16.03 0.88 Exam. 2138.43 1.88 Exam. 22 65.99 3.22 Exam. 23 25.24 1.38 Exam. 24 19.71 1.08Meropenem 18.29 1.00 Imipenem 2.39 0.13

As can be seen in Table 6, the compounds of the present invention werehydrolyzed more slowly than the standard materials, and especially thecompounds of Example 16 and 22 were very stable. Thus, the compounds ofthe present invention are useful medicaments, which overcome thedisadvantage, rapid degradation of carbapenem antibacterial agent byDHP-1 enzyme.

Test Example 5 Acute Toxicity Test

The acute toxicity of the compound of Example 14 was tested usingseveral groups of ICR mice each of 10 mice. 500 mg/kg, 1,000 mg/kg and2,000 mg/kg doses of the medicament were each intraperitoneally injectedinto each group of mice, and the temperature change, weight change anddeath were observed for 7 days after the injection. As a result, no micedied, and no distinct temperature change nor weight loss were observed.Thus, LD₅₀ was placed at a level higher than 2,000 mg/kg. The compoundof Example 14 is thus a largely non-toxic antibiotic.

While the invention has been described with respect to the abovespecific embodiments, it should be recognized that various modificationsand changes maybe made to the invention by those skilled in the artwhich also fall within the scope of the invention as defined by theappended claims.

1. A 2-arylmethylazetidine carbapenem derivative of formula (I) or apharmaceutically acceptable salt thereof:

wherein, R1 is hydrogen atom, or one or more substituents selected fromthe group consisting of C₁₋₃ alkyl, C₁₋₃ alkyloxy, trifluoromethyl andhalogen atom; and R2 is hydrogen atom or C₁₋₃ alkyl.
 2. The compound ofclaim 1, which is selected from the group consisting of:Potassium(1R,5S,6S)-2-(1-benzyl-azetidine-3-yl-thio)-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(4-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-(3-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(2-methoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(3,4-dimethoxybenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(4chlorobenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[(1-(4-fluorobenzyl)-azetidine-3-yl-thio)-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(3-trifluoromethylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-{1-[(1R)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-{1-[(1S)-1-phenylethyl]-azetidine-3-yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;Potassium(1R,5S,6S)-2-[1-(4-methylbenzyl)-azetidine-3-yl-thio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate;and Potassium(1R,5S,6S)-2-{1-[1-(4-bromophenyl)ethyl]-azetidine-3yl-thio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate. 3.A process for preparing a 2-arylmethylazetidine carbapenem derivative offormula (I) or a pharmaceutically acceptable salt thereof, whichcomprises the steps of: subjecting compounds of formula (II) and formula(III) to a condensation reaction to obtain a carbapenem ester derivativeof formula (1\0; and removing the carboxyl protecting group and theoptional hydroxyl protecting group from the compound of formula (IV)

wherein, R₁ is hydrogen atom, or one or more substituents selected fromthe group consisting of C₁₋₃ alkyl, C₁₋₃ alkyloxy, trifluoromethyl andhalogen atom; R2 is hydrogen atom or C₁₋₃ alkyl, R3 is hydrogen atom ora hydroxyl protecting group; and R4 is a carboxyl protecting group. 4.The process of claim 3, wherein step (a) is carried out by reacting thecompounds of formula (II) and formula (111) in an organic solvent underthe presence of diisopropylethylamine or triethylamine at a temperatureranging from −20 to 0° C. for 2 to 4 hours.
 5. The process of claim 4,wherein the organic solvent is selected from the group consisting ofacetonitrile, methylene chloride, tetrahydrofuran and acetone.
 6. Theprocess of claim 3, wherein the compound of formula (III) is prepared bya process comprising the steps of: (a) reacting a compound of formula(V) and epichlorohydrin in an organic solvent with stirring at roomtemperature for 24 to 48 hours to obtain a compound of formula (VI); (b)reacting the compound of formula (VI) and N-trimethylsilylacetamide inan organic solvent with heating for 3 to 5 hours to obtain a compound offormula (VII); (c) heat-refluxing the compound of formula (VII) for 3 to5 days in an organic solvent under the presence of an organic salt toobtain a compound of formula (VI); (d) dissolving the compound offormula (VID in an alcohol, adding an alkali thereto, and stirring themixture at room temperature for 30 mm to 1 hour to obtain a compound offormula (E); (e) subjecting the compound of formula (IX) to theMitsunobu reaction to obtain a compound of formula (X); and (f)hydrolyzing the compound of formula (X) in an alcohol by adding anaqueous sodium hydroxide solution to obtain the compound of formula(III)

wherein, R1 and R2 have the same meanings as defined in claim
 3. 7. Theprocess of claim 6, wherein the organic solvent used in steps (a) and(b) is petroleum ether, ethyl ether or ligroin.
 8. The process of claim6, wherein the organic solvent used in step (c) is acetonitrile,tetrahydrofuran or methylene chloride, and the organic base istriethylamine or diisopropylethylamine.
 9. The process of claim 6,wherein the alcohol used in step (d) is methanol or ethanol, and thealkali is sodium methoxide, lithium hydroxide or potassiumtert-butoxide.
 10. An antibacterial composition comprising thecarbapenem derivative of formula (I) according to claim 1 or apharmaceutically acceptable salt thereof according to claim 1 as anactive ingredient together with a pharmaceutically acceptable carrier.